1. Field of the Invention
The present invention relates to an information signal processing apparatus, a picture information converting apparatus, and a picture displaying apparatus.
2. Description of the Related Art
When an output picture signal is generated with an input picture signal in such a manner that the scanning line structure of the output picture signal is different from the scanning line structure of the input picture signal, a dedicated circuit for the output picture signal may be used. When a sum-of-product calculation is performed, a plurality of calculated results may be required. To obtain a plurality of calculated results, respective calculating circuits may be switched over. However, when the circuits are switched over, since the hardware scale may become large and the circuits may become redundant.
As a practical application, when an SD signal is converted into an output signal with high quality and high resolution, circuits corresponding to the types of output signals are disposed. A relevant circuit is used corresponding to a designated output signal. In this method, the hardware scale becomes large and circuits become redundant. To obtain an output picture signal corresponding to a picture pattern of an input picture signal, a plurality of output signals are required. It is considered that an interlace SD (standard definition) picture signal having 525 scanning lines is converted into an interlace HD (high definition) picture signal having 1050 scanning lines. Since the number of scanning lines is doubled, in the case of a natural picture, an output picture signal with high quality and high resolution is obtained. However, since the output picture signal is an interlace picture signal, in the case of a graphic picture, a line flicker becomes conspicuous. Thus, corresponding to the type of an input picture signal, the scanning line structure of an output picture signal should be switched over.
As a known method for removing a line flicker component, an interlace signal is converted into a progressive signal. However, in this method, an input signal is linear-interpolated and an interpolated signal is obtained. Thus, the resolution of the output signal cannot be improved against that of the input signal. In addition, when an interpolating method (for a still picture process or a moving picture process) is switched over corresponding to the detected result of a motion, the difference of resolution between the original signal and the interpolated signal becomes large. In particular, when a motion is incorrectly detected, the picture quality largely deteriorates.
As related inventions of the present invention, the applicant of the present invention has obtained the following US patents.
1. U.S. Pat. No. 5,379,072: Digital Video Signal Resolution Converting Apparatus
2. U.S. Pat. No. 5,666,164: Image Signal Converting Apparatus